Complete the sentences with the correct ending according to the text.
If we add a small amount of arsenic to silicon, …
As the fifth electron of arsenic attached to the nucleus very loosely …
In N-type semiconductor the electrons are …, and the holes are …
Each atom of arsenic will add …
Sometimes an electron and a hole meet and …
If a group III element is introduced into a silicon crystal, …
Gallium has …
Each atom of gallium introduces …
Gallium doped to silicon is the type of impurity called …
Introducing gallium into silicon results in the semiconductor, which is known …
Speaking
In groups describe semiconductors of n-type and p-type. Start your description like this:
If we add a small amount of arsenic to silicon…
If instead of arsenic, a group III element such as gallium is introduced into a silicon crystal…
Act as an interpreter. Translate the description of n-type and p-type- semiconductors given by your group mates from English into Russian.
Translate in writing another text about of n-type and p-type- semiconductors paying attention to new technical terms.
Electron flow in an N-type semiconductor is similar to electrons moving in a metallic wire. The N-type dopant atoms will yield electrons available for conduction. These electrons, due to the dopant are known as majority carriers, for they are in the majority as compared to the very few thermal holes. If an electric field is applied across the N-type semiconductor bar in Figure (a) below, electrons enter the negative (left) end of the bar, traverse the crystal lattice, and exit at right to the (+) battery terminal.
(a) N-type semiconductor with electrons moving left to right through the crystal lattice. (b) P-type semiconductor with holes moving left to right, which corresponds to electrons moving in the opposite direction.
Current flow in a P-type semiconductor is a little more difficult to explain. The P-type dopant, an electron acceptor, yields localized regions of positive charge known as holes. The majority carrier in a P-type semiconductor is the hole. While holes form at the trivalent dopant atom sites, they may move about the semiconductor bar. Note that the battery in Figure (b) above is reversed from (a). The positive battery terminal is connected to the left end of the P-type bar. Electron flow is out of the negative battery terminal, through the P-type bar, returning to the positive battery terminal. An electron leaving the positive (left) end of the semiconductor bar for the positive battery terminal leaves a hole in the semiconductor, that may move to the right. Holes traverse the crystal lattice from left to right. At the negative end of the bar an electron from the battery combines with a hole, neutralizing it. This makes room for another hole to move in at the positive end of the bar toward the right. Keep in mind that as holes move from left to right, that it is actually electrons moving in the opposite direction that are responsible for the apparent hole movement.